


Costume Party

by GuiltyFurry



Category: Undertale (Video Game)
Genre: Other, POV Ambiguous Character
Language: English
Status: Completed
Published: 2016-03-30
Updated: 2016-04-19
Packaged: 2018-05-30 01:12:12
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,374
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6401851
Author URL: https://archiveofourown.org/users/GuiltyFurry/pseuds/GuiltyFurry
Summary: <blockquote class="userstuff">
              <p>You and Asriel are invited to a costume party with a bunch of friends! But after a few drinks, he's looking at you from the back of the room with a mischievous look on his face...</p>
            </blockquote>





	1. Chapter 1

Imagine Asriel and you are invited to a costume party at the local club. The theme is heroes and villains, and the two of you have made a cute couples costume! You’re dressed as the fabled God of Hyperdeath, with a few liberties; your robe is actually a thigh-cut skirt with an outer layer running from your hips to your feet. Instead of full length sleeves, the robe cuts off at your shoulders and the sleeves are replaced with a pair of white dress gloves that come up to your elbows. Very classy.

Asriel is dressed as the Ambassador of the Monsters, since they are the greatest hero in modern monster history. He looks much less imposing than you; black chinos, sneakers and a blue button-up shirt with two purple stripes. The ambassador is especially important to his heritage, and he wears the casual attire with great pride.

You have a great time at the party! Asriel’s friends take him away for a bit and have some guy time with him. Meanwhile you hit the dance floor, had a few drinks and lived it up with your friends. After a while you look down the line of tables to see Asriel sitting quietly down the back where it’s only just lit up, his eyes half closed and poised on you.

You excuse yourself and head down to see how he’s going. As you get closer you can see a peculiar look on his face: he’s smiling but there’s something almost sinister about it. You ask him how he’s going and if he has a drink.

“I’m doing alright,” he purrs, barely audible over the blaring music. “And I had a few drinks with the guys. How about you, darling?” You tell him that you’ve had some drinks as well, and the dance floor is starting to wobble just a little bit. He snickers at that. You still have this feeling that something’s not quite right with him. “Why don’t you come here?” He gestures to his lap and leans back in his chair. 

What’s wrong with a little affection? You hop up from your chair and drop into his lap, only to be welcomed by the bulge in his pants. He shoots you a teasing grin as the pieces fall into place; he must be really horny. If it were a bit brighter, he’d see that the intoxicated blush in your cheeks has been replaced with an aroused blush over your whole face. You give him a playful bump while readjusting yourself to face the table. 

“What’s this?” he coos in your ear. Without any warning he grabs you roughly at the waist and lays a hand on your thigh. “Is my little pet feeling a bit risqué tonight?” He drags the hand up your leg slowly, claws leaving red marks along your skin. “How very naughty,” he whispers. His hand slips past the outer robe, underneath your skirt. He just manages to find the edge of your underwear before lifting your skirt up entirely.

“You know what I do when my pet is naughty, don’t you?” He’s hissing in your ear now, and only you can hear him. You let out a whimper and nod your head; you know exactly what he’ll do to you in front of all of your friends and his friends. But you don’t care about that: all that matters is the pulsing in his pants, grinding up against your ass.

Asriel catches your underwear with his claw and lifts you up a bit by your waist. In one motion they’re around your feet, leaving just the skirt between you and full exposure. He begins to fiddle with his own pants, but you hardly notice. Blood rushes to your head as you can feel your arousal start to drip from your nether regions. 

You want Asriel to fuck you right now. You want him to treat you like a slut in front of all these people you know, and you want to be his pet no matter how many people see. Your head is in a fog of perversion and alcohol. You catch yourself drooling out of the corner of your lips as you’re picturing yourself bent over the table and fucked senseless.

Asriel’s clearly excited as well; you can feel the tip of his cock slick with precum as he presses it against your asshole, all hidden beneath your outfit. He checks to make sure nobody’s watching, then reaches down, spreads your ass cheeks and pushes hard against your hole. The sudden pain makes you cry out, but no one can hear you over the bass pouring out of the speakers or see the tears in your eyes through the dim lighting.

You hold yourself in place, fighting the urge to stand up. Asriel thrusts out and in again, pushing further every time and making you cry out again and again. The pain is intense, but at the same time you’re enjoying it. Your head feels hot and sweat drips down the side of the face; whether it’s from the warmth of the room, those drinks that you had, the thoughts running through your head or the fact that Asriel is fucking you here and now, you can’t say. By the time his cock is completely in your ass, you’re leaning on the table and panting heavily. 

And then he stops. He’s buried so far inside you now but he’s not moving anymore. You shut your eyes tight and lean back against him, pushing him further inside you and wracking your body with ecstatic agony. He giggles as you pant into his face.

“I told you the skirt was a good idea.” The goat is gloating at you, which makes you feel even more turned on. You look in his eyes and grind just a little into his crotch. Bliss is starting to outweigh the ache in your rump. As you work his cock inside of you, Asriel’s just smirks, nothing showing that he’s even enjoying himself.

“It’s a bit risky, don’t you think?” His half-lidded eyes and the lust in his voice are driving you crazy. You can’t muster up the words to respond, so you nod your head vigorously. He chuckles before continuing. “No no, my sweet. I meant to help you.” He’s right; it’d be risky if hands went under your skirt. “Looks like you’ll just have to…” He pauses to flash you a toothy grin. “Sit this one out.” He thrusts up to punctuate his words, sending a jolt throughout your body.

“Heya kids, what’re you up to?”

Your head shoots around to see one of your friends make their way to your table. The blush in your cheeks spreads right across your face but your body begins to turn ice cold. You wanted to be fucked in public but you didn’t want this!

“Howdy,” Asriel pipes in in his regular tone. You manage a wonky smile. “We’re just having a bit of quiet time in the back here, keeping it cool, y’know.”

Your friend turns their attention to you. “Hey, you’re not looking to good,” they say with a scrunched up look of concern. “You okay?” You respond with a weak shake and blow the hair out of your eyes. They lean down and lay a hand on your forehead and feel the cold sweat clinging to your skin. “Aw damn, that sucks.”

“Yeah, I think we’ve maybe had a few too many drinks,” Asriel replies for you. He shifts in his seat, grinding his cock inside of you. You whimper and grab your stomach, trying to play it off as illness. “Aww, tummy ache,” he says. His voice is full of concern, but you know he’s mocking you, taking great pleasure in what he’s doing.

“Do you need some water?”

“No!” You answer in a sudden frenzy. Why won’t they just leave? “I just need to…” You gulp and take a breath. “Need to rest a bit…” Your voice trails off as Asriel leans forward slowly and you feel him stretch your inner walls even further.

Asriel gives you a gentle hug and rubs your shoulder lightly. “I think we’ll head home in a bit,” he tells your friend. “This one needs to get to bed.” He squeezes your shoulders and leans back again. You nod slightly, clenching around Asriel as he drags his cock back outwards.

“Alright then, I’ll see you guys later then.” Finally! Your friend smiles and brushes your hair aside. “Get better soon!” They turn around and walk away. Asriel waves as they leave and thrusts hard into your ass. You fall forward with a yelp, but his other hand is gripping your hip tight. 

“Mmm.” His voice is dripping with lust again. “You handled that well, didn’t you, pet?” You’re almost spread out on the table again, hands grasping at the tablecloth. Your nerves are on fire and all that you want is sweet release. “I thought this was a punishment for you, but maybe you deserve a reward?” he taunts. His hips start to move in a subtle rhythm, his cock dragging back and forth by an inch or two with each thrust.

Your inhibitions are completely gone now. Every push releases a sharp moan from your open mouth, tongue almost hanging out, drool seeping out of the corners of your lips. You push back on his crotch as he shifts forward, driving him in. His pace quickens a bit, then a bit more. Anyone looking your way now would soon realise that you’re splurged out on the table while Asriel is thrusting behind you.

You look around at the crowd to see that, miraculously, no one is watching. The heat returns to your body as your lover fucks you behind the crowd of friends and acquaintances. You’ve never felt this turned on before; you can tell by just how much you’re leaking beneath your skirt. Asriel keeps pumping into you, and you can hear him grunting roughly now.

“Get ready-un! My li-little slut!” He grabs your hips and digs his claws into your thighs. A few more thrusts and he finally cums, shooting his creamy load as deep inside of you as he can manage. He pushes in hard, and you let out a soft cry of ecstasy. You forget everything around you and focus on the hot cum spreading itself through your ass.

Asriel sits for a while, still inside you. You’ve clenched around him, trying to keep his seed inside of you for as long as you can. You keep panting, your body is shaking; you still crave to release the pressure in your loins. You manage to turn your head enough to catch Asriel’s face as he smiles at you.

One arm around your waist, he lifts you off of him again. His semi-hard dick slides out of you along with a glob of cum, staining his pants. He adjusts himself and manages to zip his pants up with one hand before lowering you back down. You attempt to push yourself off of the table, and manage after a quick falter that almost sent you back down. You can feel the warmth of his seed spread down to your open hole.

You reach down slowly for your underwear around your ankles. Asriel watches as you lift them back up your legs and under your skirt, fumbling a bit as you try to stand up. When you sit back down, you can feel his load still trying to flow outwards, now dammed by your underwear.

“Time to go, I think,” he says, lifting him and you to your feet. He guides you towards the exit with one hand around your waist. He leans down to whisper into your ear, “we need to get you cleaned up, pet.” A shiver runs through your body as your muddled brain conjures up images of Asriel fucking you again before cleaning you up. You just know that you’re going to have the time of your life back at home.


	2. Afterparty

**Summary for the Chapter:**

> I hadn't intended on writing a sequel/second chapter, but someone seemed interested.   
> Things get a little rough back at home because you just couldn't keep your mouth shut...

It’s a struggle, but you manage to open the door to your apartment with Asriel’s tongue invading your mouth and your lips locked with his. He pushes you threw the entrance and slams the door behind him, moaning into your mouth. His hands move back to your body, sliding up and down your sides, making their way past the fabric and finding your skin. You grab his face, pulling him even closer into you.

He guides you into the lounge room. You can smell the sweat on his forehead and the back of his neck, combined with his musk and the lingering scent of his seed still inside you. Your body is still aching for more; more of his cock, more of his tongue, more of your own pleasure. You kick your shoes off and throw your belongings to the floor. Asriel follows suit, breaking the kiss to fling his keys away and pull his belt off. You waste no time in grabbing his shirt and ripping the front open, buttons flying in the process.

You only just get a chance to behold your lover’s physique under his shirt before he scoops you up again, lifting you off your feet and carrying you to the bedroom. You nuzzle into the crook of his neck, planting hungry kisses beneath against the skin beneath his fur. You’re deposited onto the bed and he crawls on top of you, repaying your kisses by running his tongue along your neck and down your throat. Every now and then he stops to bite and suck at your skin.

You writhe beneath him and run your hands along his chest and waist, grabbing fistfuls of fur and pulling him closer towards you. His bulge brushes against your crotch, sending a tingle throughout your body. You keep pulling him closer but he keeps playing with your neck, occasionally moving up to lightly nip at an ear or cheek.

You moan his name, “Asrieeeel”, dragging it out as he drags the back of his claws along your belly. “Asriel, I need mo-ha! More!” You were interrupted as he sank his claws in just a little bit, not enough to break the skin. The pain is addictive, driving your senses even crazier, if that were possible.

Asriel looks down at you, subtle mischief mixed in with that gorgeous, sincere grin he has. “In time, my love,” he responds, planting a soft kiss on your cheek. That’s not the response you need at all!  
You thrust upwards and grind against him. “Now, you prick.” You don’t mean to say it but it’s too late to take it back. And honestly, he’s already had his way once; now it’s your turn. 

Asriel looks down at you, suddenly impatient. “You’re a bit feisty, aren’t you?” You thrust again in response. He sighs and climbs off, making to take of his pants. He reaches down to your underwear and, with a flick of his claw, slices the fabric around your hips and exposing your lower body. He lifts your skirt up and starts to press his cock against your ass, still sticky and a bit stretched from earlier.

As he pushes himself inside you can feel the leftover cum inside you being pushed further in. There’s a bit of discomfort as he stretches your walls, but nowhere near as painful as it was before. The ecstasy is still there, even better than before now that you can cry out again.

It’s not long before he’s balls deep in you once more. Without waiting for you to prepare yourself, he pulls out and thrusts in again. You yelp in surprise and grab the bed sheets around you, bracing yourself for the next thrust. Asriel bucks his hips roughly while he’s still inside, filling you more than he thought was possible. He grunts under his breath with each thrust. He’s not usually this hardhearted when it comes to sex. Maybe he’s a bit hurt from before. Then again…

A cruel thought crosses your mind. You look up at him, trying to get his attention. “Hey!” you call out. Asriel looks into our eyes, a flicker of annoyance across his face. “Is tha-that, all you got?” You don’t sound very convincing; he’s still inside you, still thrusting deep and making your thoughts a barely coherent mess.

He huffs and steps back. “You can do better?” he shouts. That’s all the invitation you need; you sit back up, snake your arms around his neck and kiss him deep. His hands lay on your hips and he pulls you in tighter, his dick pressing against our thighs. You can feel a tingling sensation run through your lower body at his touch; his hands are warm and his paw pads smooth. You pull him to the side, setting him up in front of the bed. You pull away and give him a gentle shove. 

“Lay back,” you command. He moves to the centre of the bed. You crawl along the bed on hands and knees, positioning yourself above him. You give him a peck on the lips before sitting back, pushing his manhood against your ass. It should be easy enough now for you to take him in, but he grabs your hips anyway to support you.

You begin to sit further back, but something’s wrong. He won’t fit. As you look down at him, puzzled, he flashes a cruel grin. “Well? Go on, then” He squeezes your hips tighter and begins to push you down. There’s a sharp pain again as his cock breaches your ass hole, and continues to push through. You start to pant at the effort, and you’ve only just begun.

“Didn’t expect that, did you?” There’s something different about him now. His eyes have changed; now they’re black with white pupils. You’ve heard of it happening before, but never seen it yourself. It’s intimidating, you think to yourself, but you can’t suppress the shiver of excitement running down your spine.

He’s still pulling you down onto his member, so slowly but still painfully. You let out a wordless scream. Your body betrays you, still waiting for more pleasure and finding it as Asriel fills your ass again, as if he hadn’t already. The pain clears your thoughts, but your thoughts are still focused on how much you want to ride him for the rest of the night.

It takes a while, but he finally loosens his grip on your body, just as you can feel his thighs press against your ass cheeks. You collapse forward onto his chest, taking deep breaths. You look up, barely seeing his face through the sweaty hair plastered against your face. His lips are closed but still curled up into a smile. “I’m still waiting, pet.”

You chuckle, then push off of his chest and sit back up. His cock shifts inside you, filling you just a bit more. You put all of your strength into our legs and push yourself up slowly, extracting every bit of pleasure from every bit of Asriel inside of you. The pain numbs quite quickly, considering what you just went through. As you slide back down his shaft, it’s gone almost entirely. You realise he’s still holding onto your waist, and the tingling in your sides tell you he’s using more magic to erase the pain.

You pick up the pace, bouncing up and down on his cock. Before long Asriel starts thrusting in time, pushing deeper inside of you as you move down. The pleasure is building up inside of you, and you can feel your orgasm finally approaching. “Asriel!” you cry out. “Asriel, I-I think… oh god, I’m-”

He interrupts you. “No, you’re not. But I am.” Before you realise what’s happening, he holds your body tight and pushes you all the way down on his shaft. You start grinding with it inside of you as he thrusts into you, shallow but rough. The feeling in your genitals feels ready to burst like a spring coiled far too tightly. Your legs begin to shake, then give out entirely.

With a howl, he empties himself inside you. You can feel his cum shoot up into your ass, warm and creamy. He shoots more and more of his spunk into you. Each thrust draws some of it out, and suddenly you can feel it running out of your ass, down his cock and gathering in his fur. You look up; his head is turned up, eyes shut tight and teeth bared.

You wait for your own climax to take over, but nothing happens. That spring in your crotch won’t let go, and you begin to groan on top of your lover. He looks back down, his snarl turning into a smile. “What’s the matter?” he chuckles. “Not enjoying yourself anymore?” He playfully thrusts again, eliciting a moan from your lips and spilling even more cum.

It’s not over for you yet. You draw up your courage and look him in the eyes. “Well…” it takes you a bit to catch your breath. “I just figure… that you could…” His smile stretches even further than you thought possible, and his unnerving white pupils stare back into your own. You shoot him a smirk.

“You know… actually pleasure your partner.” His expression drops in an instant. His eye twitches just a bit. Black lines begin to spread from the back of his neck towards the middle of his cheeks like thick tentacles. You can hear him growling from the bottom of his throat. Now you’ve done it.

“You bitch!” The next few seconds are a blur of motion: you feel yourself lifted into the air, cum flowing from your ass. You’re spun around, facing the end of the bed, and forced onto your knees. Asriel is up and behind you, his claws ripping the clothes from your back, tatters falling around your body.

“Obviously I need to teach my pet some more respect!” In a single thrust, the God of Hyperdeath hilts himself in your ass. You scream out; His transformation made His cock much bigger. You’re more stretched than you can comprehend right now. As if you haven’t had enough pain already, you can feel a stinging around His shaft, and it feels like this won’t go away as quickly as last time.

Asriel ruts you at full force. His balls slap against your thighs with every thrust, and His seed is pumped out of you. You bury your head in the mattress and grab the sheets around you. You can’t help but scream into the bed. The feeling in your crotch won’t go away; every second feels like you’re about to cum, but you never do.

You feel His weight push against your body as he leans down over you. “Say my name,” he growls into your ear. Your only response it to moan long and loud into the mattress again. A hand grabs your shoulder and pulls your head up. “Say it!”

“A…asriel…” Your mind is too clouded for thought. You’re being driven insane by the orgasm that isn’t coming, and your legs are slipping out from underneath the God of Hyperdeath. Claws sink into your shoulder, drawing blood. You cry out in shock and look behind you into Asriel’s face.

“That’s right, pet. And what should you call me?” He hasn’t stopped fucking you, but now he changes pace. Instead of thrusting at full force, he starts to move very slowly, excruciatingly slowly, drawing out pleasure as you feel every muscle of His dick press against the inside of your ass. 

You moan out your response right into His face, “mmmmmmmmmmmaster…” He thrusts the rest of His cock inside and pulls out again just as quickly, then goes back to His slow pace.  
“Again.”

“Master…” Another thrust.

“Once more.”

“Master!” You shout it into His face. He thrusts again.

“That’s right,” he coos, “and you’re my bitch, aren’t you?” He speeds up now, a much more comfortable pace for your body. You nod in response, but he shakes His head. “Say it.”

“Yes!”

“Yes what?” He all but stops moving, denying you your ecstasy.

“I’m your bitch, master!”

And with that, he fucks you once more, reaching around and stroking your genitals. His touch is almost painful because of how much pleasure has built up inside your crotch. With another howl, he presses your shoulder down hard, forcing you into the mattress, and cums again. 

After the first shot of His seed spreads inside of you, he pulls His shaft out and unloads himself onto your back. His cum is heavy, hot, creamy. You can feel it running down your back, spreading out and falling down your sides. Each throb of His cock spreads more of the sharp-smelling cum over you. It even makes its way down to your neck.

The sensation feels so good, and finally you cum with a loud scream. Your climax fills your entire body, making you shake with each pulse. You can feel our own fluids running down your crotch and puddling on the sheets beneath you, staining them along with Asriel’s cum. You can’t stop cumming; His hand strokes your crotch gently now, but you keep throbbing at His touch.

It takes a couple of minutes for the both of you to calm down. You collapse into the messy sheets, not giving a damn about the mess on your front or back. Asriel drops just beside you, making you bounce on the mattress. Both of you are drenched in sweat; that combined with both of your fluids fills the room with the pungent smell of sex that you've come to love.

You turn your head around and look into Asriel’s eyes, finally catching your breath and feeling your heart slow down. The markings on his face are gone, and his eyes are back to their deep red.  
He shoots you a smile. “You’re such a trash talker,” he says, laughing at his own joke. 

You nod back. “I’m no match for you,” you reply.

“Does that mean you’re gonna talk shit like that again, my pet?” He flashes his teeth at that last part.

You give him a smug grin back. “Absolutely.”


End file.
